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Fully-functional RTX 3070 16GB gets frankensteined into existence by harvesting dead PCBs and RX 6800 XT's VRAM chips — doubles frame rate in games like Spider Man 2 at 4K and includes switch for 8GB mode
A tech enthusiast has combined an Nvidia GeForce RTX 3070 (8GB) with defective memory and an AMD Radeon RX 6900 XT (16GB) with a damaged GPU. The result was a working RTX 3070 with 16GB of VRAM. While the mod by ComputerBase reader AssassinWarlord seems like a great success, especially in VRAM-hungry modern AAA gaming, there are a couple of small wrinkles to be aware of.
A memory boost for the RTX 3070 is an upgrade that would make many people happy. While the RTX 3070 GPU is significantly more potent than its little brother, the RTX 3060 12GB, modern titles have started to hit the boundaries of the VRAM more often. This may be one of the reasons that rumors are swirling about a reanimated RTX 3060 arriving in the coming months, rather than the RTX 3070.
Back to the mod details, and AssassinWarlord started by taking the eight BGA memory chips off both donor cards, then reballed the ICs. Desoldering and reballing chips like these isn't for the casual hobbyist, so we'd characterize AssassinWarlord as a high-level tech tweaker. They also 3D printed a bracket for a GDDR6 reballing stencil... Commenting on the hardware aspect of the process, the intrepid modder summed up that it was "actually not that difficult, the whole thing." (machine translation from German). However, a little bit more effort was needed, such as a resistor change to get the system to see 16GB of VRAM, and a VRAM config switch would be added later.
AssassinWarlord commented that, as well as jumpers for different VRAM chip brands, the original RTX 3070 design was fine with 16Gb Samsung memory ICs (so, 8x 2 GB chips), which are needed to configure the graphics card with 16GB of VRAM total.
No extra software or hardware mods were needed to successfully test the RTX 3070 16GB in modern Windows tools and games, but a wrinkle remained in this otherwise perfect mod, which works with standard GeForce drivers. In short, the system would black screen after closing a tool that stressed the GPU subsystem.
Some investigative work indicated that memory timings set in BIOS were the underlying problem in the 16GB configuration. A RegEdit 'DisableDynamicPstate' solution to this issue was produced, meaning the GPU wasn't downclocked (or black screens) after being taxed, but this results in an idling power consumption of approximately 70W.
The forum source thread contains a few before and after synthetic benchmarks with various GPU and memory clocks tested. But it is only really in some modern games that we get to see the true advantage of the RTX 3070 16GB. Specifically, AssassinWarlord tested Marvel's Spider-Man 2 like-for-like (4K Very High) with the 8GB and 16GB switch modes. The frame rate doubles from the ~20 fps region to 40 fps+ with the 16GB enabled - see below.
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We've seen a couple of RTX 3070 modded to 16GB VRAM projects before. However, AssassinWarlord's effort is admirable for making use of two non-working cards to make one very usable model. Moreover, the hardware switch, 16GB script, and the avoidance of any need for modded drivers are appreciated.
Mark Tyson is a news editor at Tom's Hardware. He enjoys covering the full breadth of PC tech; from business and semiconductor design to products approaching the edge of reason.
